David's work in the field of life extension began after his wife's terrifying diagnosis. "I went everywhere in the world trying to figure out how to save her life," he says. "Wherever I went, I realized that we had not been eating right."
He tried to find doctors who could save his wife, but the disease advanced too quickly. "The cancer got in her lymph nodes, and finally, she died," he says. "With that I said, 'What I want to do is find a cure for cancer.' I wanted to solve it, because I was very much in love."
David opened the North Carolina Research Center, one of the country's premiere life extension research labs, and changed the way he lived his life.
During a visit to David's home, Oprah sees how a diet of natural foods and commitment to exercise can change our definition of "old age."